How to scan users logging on less than once a week?

Hi,

A question I haven't been able to find the answer to:

I have laptop users not logging on the network more than once a week/every other week - what's the best way to capture these PC's?

- Do I do a "Refresh Inventory Assessment"? (The text tells me I should only do this when the scan hasn't been completed normally) 
- Do I have to create a new DB and redo the whole scan?
- Other method(s)?

My understanding is that MAP does a snapshot when the inventory is run and doesn't scan an object twice, so if MAP finds the computer object in the AD that isn't online at the scan - will it attempt to scan it if I would do a refresh inventory assessment when it is online?

Thanks in advance,
...Stefan